I am writing a bash completion program in Golang. In fact, the program is its own completion program as it looks for the COMP_LINE environment variable and if it is present, it outputs the completion options, and if not, just proceeds to run the main program.
The completion is then installed with the following:
complete -C /path/to/my-program my-program
This works well. For most of my completions, I want a space to be added after the word has been completed, however for a few flags I do not want this to occur.
When completion is defined, you can set a -o nospace option to omit the trailing space when completing a word. However then all completions that need a space have to have one added explicitly to the completion word list.
Is there any way that my program can modify the complete opts dynamically based on what completion it is returning? Is this exposed as an environment variable that a completion command could set?
I would like to avoid having to append a space to all other completions just to avoid one in the edge case for the one flag I don't want that to happen on.
My Perl framework (Perinci::CmdLine) also does the same: the scripts are their own completion, activated using complete -C SCRIPTNAME SCRIPTNAME (when the script is in PATH). Completing using an external command has its pro's and con's compared to using shell function. To solve the problem you encountered, I output a dummy answer with an extra space. Since there are more than one answer, bash no longer automatically adds a space. So instead of just returning (in JSON notation):
["-o"]
you return:
["-o","-o "]
I also use this trick when doing path completion. To allow user completing a path by "drilling down", when there is a single directory match I output:
["dirname/","dirname/ "]
so the user can Tab again to drill down inside path instead of getting a space after "dirname/ " and having to backspace and Tab again.